#include <iostream>
#include <string>
#include <cstring>
using namespace std;
 
void c_function(char * dest) {
	strcpy(dest, "FOOO");
}
 
 
template<std::size_t max>
struct string_filler {
  char data[max+1];
  std::string & destination;
  string_filler(std::string & d) : destination(d) {
    data[0] = '\0'; // paranoia
  }
  ~string_filler() {
    destination = data;
  }
  operator char *() {
    return data;
  }
};
 
int main() {
	string foo;
	c_function(string_filler<80>{foo});
	cout << "foo contains \"" << foo << "\"" << endl;
	return 0;
}

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